And I'm Audie Cornish. Our top story today that we're covering throughout the program is the mass shooting in Newtown, Connecticut. And we can now confirm, based on the word of multiple federal law enforcement officials, that the alleged gunman is 20-year-old Adam Lanza. He allegedly arrived at Sandy Hook Elementary School around 9:30 this morning. He fired into two rooms. In all, 20 children are confirmed dead. There are also six adult victims at the school as well as another adult victim at a family home of the shooter.

Authorities have confirmed that the gunman is also dead, though to be clear, they have not yet confirmed his identity. For more, we turn to NPR's Carrie Johnson. And, Carrie, this has been such a confusing episode. The information's been changing all day. At this point, what do we know about the identity of the shooter and his victims?

CARRIE JOHNSON, BYLINE: Yes, Audie. The information coming out of Connecticut and here through Washington has been mischaracterized throughout the day as people try to figure out what happened in that school. Right now, at this point, what we do know from multiple - the word of multiple federal law enforcement sources is that the gunman was Adam Lanza, a 20-year-old young man whose mother taught at the school. [POST-BROADCAST CORRECTION: Nancy Lanza, the mother of Adam Lanza, was not associated with Sandy Hook Elementary School.]

He is dead at the scene of the school. And among the victims were 18 kids who died at the school, two others who died en route or at nearby hospitals.

The shooter himself, as I said, is dead at the school. And there's one dead adult described as being at a family residence in Newtown. There's been conflicting information today about who that person is. We believe it's Lanza's mother. But authorities from the Connecticut State Police who are leading this investigation have not gone on the record and confirmed that nor have they confirmed the identity of the dead gunman at this point.

CORNISH: Now, how did this incident unfold at the school? Walk us through it.

JOHNSON: Based on what we know now from Lieutenant Paul Vance of the Connecticut State Police, who's been the primary law enforcement briefer on this matter, they got some 911 calls around 9:30 in the morning that an emergency was talking place. Lieutenant Vance says the shootings took place in two rooms in just one area or one section of the school, and things took place very quickly. We know from other sources that as many as three weapons were recovered at the scene or in the parking lot. One of them appears to have been a Bushmaster rifle, the same weapon used in the D.C. sniper shootings. There may also have been some handguns with the ability to carry large numbers of ammunition as well.

CORNISH: Now, what are authorities continuing to investigate at this point?

JOHNSON: OK. So Lieutenant Vance of the Connecticut State Police pointed out that they're looking at every ancillary circumstance - law enforcement speak. What that means is did he have any help? What was his state of mind in advance of these shootings? Were there any warnings or any booby traps he may have set? And they're getting some help from Ryan Lanza, the alleged gunman's 24-year-old brother who's been cooperating with authorities and appears to not have taken any part in this rampage.

CORNISH: That's NPR's Carrie Johnson. Carrie, thank you so much for talking with us.

JOHNSON: Thank you.

CORNISH: And we can now confirm also that based on the word of multiple federal law enforcement officials that the alleged gunman is 20-year-old Adam Lanza. Transcript provided by NPR, Copyright NPR.